Communication control device, communication control method, and communication control system

ABSTRACT

Provided is a communication control device including an information acquisition unit acquiring first information concerning a position a guard area for a first wireless communication system and second information concerning a position of a master node of a second wireless communication system which is secondarily operated using a frequency channel used by the first wireless communication system, a determination unit determining, using the first information and the second information acquired by the information acquisition unit, whether or not an interval between a reference point of the first wireless communication system and the master node meets a condition which depends on a width of the guard area and a communication distance assumed for the second wireless communication system, and a control unit causing the second wireless communication system to be operated with a given transmission power if the determination unit determines the interval meets the condition.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 14/238,277, filed Feb. 11, 2014, which is aNational Stage of PCT/JP2012/065483, filed Jun. 18, 2012, and claims thebenefit of priority from prior Japanese Patent Application JP2011-184323, filed Aug. 26, 2011, the entire content of which is herebyincorporated by reference.

The present disclosure relates to a communication control device, acommunication control method, and a communication control system.

BACKGROUND ART

Secondary usage of a frequency channel is discussed as a method foralleviating future depletion of frequency resources. The secondary usageof a frequency channel is that part of or all the frequency channelspreferentially allocated to a system is secondarily used by the othersystem. Typically, a system which is preferentially allocated with afrequency channel is called primary system and a system whichsecondarily uses the frequency channel is called secondary system.

A TV white space is an exemplary frequency channel whose secondary usageis discussed (see Non-Patent Literatures 1 and 2). The TV white space isa channel which is not used by a TV broadcast system depending on anarea among frequency channels allocated to the TV broadcast system as aprimary system. The TV white space is opened to a secondary system sothat the frequency resource can be efficiently utilized. A standard fora physical layer (PHY) and a MAC layer for enabling the secondary usageof the TV white space can employ IEEE802.22, IEEE802.11af and ECMA(European Computer Manufacturer Association)-392 (CogNea, see Non-PatentLiterature 3 described later).

The secondary system is generally required to operate so as not to givean excessive interference to the primary system during the secondaryusage of the frequency channel. An important technique therefor istransmission power control. For example, Patent Literature 1 describedlater proposes therein a method for calculating a path loss from a basestation as a master node of a secondary system to a reception device asa primary system and a discrete frequency width between frequencychannels and determining maximum transmission power of the secondarysystem based on the calculation result.

CITATION LIST Non-Patent Literature

Non-Patent Literature 1: “SECOND REPORT AND ORDER AND MEMORANDUM OPINIONAND ORDER”, [online], [searched on Aug. 15, 2011],Internet<URL:http://hraunfoss.fcc.gov/edocs_publidattachmatch/FCC-08-260A1.pdf>Non-Patent Literature 2: “Standard ECMA-392 MAC and PHY for Operation inTV White Space”, [online], [searched on Aug. 15, 2011],Internet<URL:http://www.ecma-international.org/publications/standards/Ecma-392.htm>

PATENT LITERATURE

-   Patent Literature 1: JP 2009-100452 A

SUMMARY OF INVENTION Technical Problem

Generally, the secondary system includes a master node as a devicevoluntarily operating the secondary system and a slave node as a deviceparticipating in the secondary system by connecting with the masternode. Naturally, not only a wireless signal transmitted from the masternode but also a wireless signal transmitted from the slave node may givean interference to the primary system. However, in a case where aposition of the slave node is not known at the start of operating thesecondary system or the slave node is moved, and so on, it is difficultto accurately predict an influence of the wireless signal transmittedfrom the slave node. Moreover, if the transmission power is to beindividually controlled for each slave node, a mechanism for controllingthe transmission power is complexed.

Therefore, it is preferable to provide a simple mechanism able toprevent the wireless signal transmitted from the slave node from causingan excessive interference upon operating the secondary system.

Solution to Problem

According to an embodiment of the present disclosure, there is provideda communication control device including an information acquisition unitacquiring first information and second information, the firstinformation concerning a position a guard area for a first wirelesscommunication system, the second information concerning a position of amaster node of a second wireless communication system which issecondarily operated using a frequency channel used by the firstwireless communication system, a determination unit determining, usingthe first information and the second information acquired by theinformation acquisition unit, whether or not an interval between areference point of the first wireless communication system and themaster node meets a condition which depends on a width of the guard areaand a communication distance assumed for the second wirelesscommunication system, and a control unit causing the second wirelesscommunication system to be operated with a given transmission power ifthe determination unit determines the interval meets the condition.

According to an embodiment of the present disclosure, there is provideda communication control method, for a communication control devicecontrolling a second wireless communication system which is secondarilyoperated using a frequency channel used by a first wirelesscommunication system, the method including acquiring first informationand second information, the first information concerning a position of aguard area for the first wireless communication system, the secondinformation concerning a position of a master node of the secondwireless communication system, determining, using the acquired firstinformation and the second information, whether or not an intervalbetween a reference point of the first wireless communication system andthe master node meets a condition which depends on a width of the guardarea and a communication distance assumed for the second wirelesscommunication system, and causing the second wireless communicationsystem to be operated with a given transmission power if the interval isdetermined to meet the condition.

According to an embodiment of the present disclosure, there is provideda communication control system including a master node of a secondwireless communication system which is secondarily operated using afrequency channel used by a first wireless communication system, and acommunication control device which controls operation of the secondwireless communication system performed by the master node. Thecommunication control device include an information acquisition unitacquiring first information and second information, the firstinformation concerning a position of a guard area for the first wirelesscommunication system, the second information concerning a position ofthe master node, a determination unit determining, using the firstinformation and the second information acquired by the informationacquisition unit, whether or not an interval between a reference pointof the first wireless communication system and the master node meets acondition which depends on a width of the guard area and a communicationdistance assumed for the second wireless communication system, and acontrol unit causing the master node to operate the second wirelesscommunication system with a given transmission power if thedetermination unit determines the interval meets the condition.

Advantageous Effects of Invention

According to the present disclosure, the wireless signal transmittedfrom the slave node can be prevented from causing an excessiveinterference upon operating the secondary system.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram for explaining an interference aprimary system suffers upon secondary usage.

FIG. 2 is an explanatory diagram for explaining an in-band interferenceand a between-band interference.

FIG. 3 is as explanatory diagram for explaining a configuration of acommunication control system according to one embodiment.

FIG. 4 is a sequence diagram illustrating an exemplary schematic flow ofa communication control processing performed in the communicationcontrol system according to one embodiment.

FIG. 5 is a block diagram illustrating an exemplary configuration of asecondary system manager according to one embodiment.

FIG. 6 is an explanatory diagram for explaining an exemplary parameterregarding a distance used in one embodiment.

FIG. 7A is a flowchart illustrating an illustrative first scenario of apower allocation processing by the secondary system manager.

FIG. 7B is a flowchart illustrating an illustrative second scenario ofthe power allocation processing by the secondary system manager.

FIG. 7C is a flowchart illustrating an illustrative third scenario ofthe power allocation processing by the secondary system manager.

FIG. 8 is a block diagram illustrating an exemplary configuration of amaster node of the secondary system according to one embodiment.

FIG. 9 is a flowchart illustrating a first example of the flow of thecommunication control processing by the master node.

FIG. 10 is a flowchart illustrating a second example of the flow of thecommunication control processing by the master node.

FIG. 11 is an explanatory diagram for explaining an exemplary parameterregarding a distance used for an interference control between thesecondary systems.

FIG. 12 is a flowchart illustrating an exemplary flow of the powerallocation processing by the secondary system manager for theinterference control between the secondary systems.

DESCRIPTION OF EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the drawings, elements that have substantiallythe same function and structure are denoted with the same referencesigns, and repeated explanation is omitted.

A description will be given in the following order.

1. Outline of system1-1. Problem relating to first embodiment1-2. Outline of communication control system2. Exemplary configuration of secondary system manager2-1. Explanation of units2-2. Flow of process3. Exemplary configuration of master node3-1. Explanation of units3-2. Flow of process4. Application to interference control between secondary systems

5. Conclusion 1. OUTLINE OF SYSTEM

First, with reference to FIG. 1 to FIG. 4, a description will be givenof a problem relating to a first embodiment and an outline of acommunication control system.

[1-1. Problem Relating to First Embodiment]

FIG. 1 is an explanatory diagram for explaining an interference aprimary system suffers upon secondary usage. With reference to FIG. 1,there are illustrated a primary transmission station 10 for providingservices of the primary system, and a primary reception station 20positioned within a service area for the primary system. The primarytransmission station 10 may be a TV broadcast station, or a wirelessbase station or repeater station in a cellular communication system, forexample. The cellular communication system may include the GSM, UMTS,WCDMA, CDMA2000, LTEm, LTE-Advanced, IEEE802.16, WiMAX or WiMAX2, andthe like. When the primary transmission station 10 is a TV broadcaststation, the primary reception station 20 is a receiver having anantenna or tuner for receiving TV broadcast. When the primarytransmission station 10 is a wireless base station in a cellularcommunication system, the primary reception station 20 is a wirelessterminal operating in accordance with the cellular communication system.In the example of FIG. 1, a channel F1 is allocated to the primarytransmission station 10. The primary transmission station 10 provides TVbroadcast services, wireless communication services or some otherwireless services by transmitting wireless signals on the channel F1.FIG. 1 also shows a boundary 12 of the service area and an outer border14 of a guard area for the primary system.

FIG. 1 further shows master nodes 200 a, 200 b, and 200 c each operatingthe secondary system. Each of master nodes uses the channel F1 allocatedto the primary system or near channel (e.g., channel F2) to operate thesecondary system respectively. In the example of FIG. 1, a slave node202 a participates in the secondary system operated by the master node200 a on the channel F1. Slave nodes 202 b and 202 c participate in thesecondary system operated by the master node 200 b on the channel F1. Aslave node 202 d participates in the secondary system operated by themaster node 200 c a channel F2. Here, the master node of the secondarysystem may be a wireless access point which is compliant with orpartially uses a wireless communication system such as IEEE802.22,IEEE802.11, or ECMA, or may be a wireless base station or repeaterstation which is compliant with the cellular communication system orpartially uses standards thereof. If the secondary system is operated inaccordance with the cellular communication system, the cellularcommunication system may be the same as or different from that of theprimary system. The slave node of the secondary system is a wirelesscommunication terminal supporting the wireless communication system thesame as the master node. The master nodes 200 a, 200 b, and 200 c mayoperate the secondary system in accordance the same wirelesscommunication system, or may operate the secondary system in accordancewith the wireless communication systems different from each other. Atleast the master node of the secondary system is typically prohibitedfrom operating within the guard area for the primary system byregulations. The slave node may be also prohibited from operating withinthe guard area.

Under the circumstances such as of FIG. 1, the primary reception station20 may be influenced by an interference due to the wireless signalstransmitted from secondary transmission stations (both master node andslave node). FIG. 2 is an explanatory diagram for explaining an in-bandinterference and a between-band interference. In the example of FIG. 2,the channel F1 is a use channel of the primary system. The channel F2 isa channel adjacent to the channel F1. The channel F3 is a channeladjacent to the channel F2. A guard band is provided between the channelF1 and the channel F2, and between the channel F2 and the channel F3.However, even if these channels F2 and F3 are used by the secondarysystem, as illustrated in FIG. 2, a considerable interference may occurfrom a near channel (such as channels F2, F3 and other channels) due toout-band radiation.

In the example of FIG. 1, the slave node 202 a is positioned closer tothe primary reception station 20 than the master node 200 a. For thisreason, if the slave node 202 a uses a transmission power equivalent tothat of the master node 200 a, the wireless signal from the slave node202 a may give an excessive interference to the primary receptionstation 20. On the other hand, the slave nodes 202 b and 202 c arepositioned farther from the primary reception station 20 than the masternode 200 b. For this reason, even if the slave nodes 202 b and 202 c usea transmission power equivalent to that of the master node 200 b, thewireless signal from each slave node 202 does not give an excessiveinterference to the primary reception station 20. The same goes for theslave node 202 d.

With existing method, each master node of the secondary system controlsthe transmission power used by the master node and slave node in thesecondary system in order to restrict the interference given to theprimary system. However, in a case where the position of the slave nodeis not known at the start of operating the secondary system, or theslave node is moved, and so on, if the transmission power for the slavenode is to be dynamically controlled in response to appearance, move anddisappearance of the slave node, a mechanism for controlling thetransmission power exceedingly becomes complex. Moreover, an overhead ofsignaling increases. Therefore, it is preferable to provide a mechanismable to stably prevent the interference to the primary system using asimpler mechanism.

[1-2. Outline of Communication Control System]

FIG. 3 an explanatory diagram for explaining a configuration of acommunication control system 1 according to one embodiment of thetechnology of the present invention. With reference to FIG. 3, thecommunication control system 1 includes the primary transmission station10, a data server 30, a secondary system manager (SSM) 100, and a masternode 200. Here, in the example of FIG. 3, only one master node 200 isillustrated, but actually more master nodes may exist. One or more slavenodes 202 participate in the secondary system operated by the masternode 200.

The data server 30 is a server device a having a database storingtherein data on secondary usage. The data server 30 accepts an accessfrom the master node 200 to provide data indicating secondarily usablechannels and position data of the transmission station 10 of the primarysystem to the master node 200. Additionally, the master node 200registers information on the secondary system in the data server 30 atthe start of the secondary usage. Communication between the data server30 and the master node 200 may be made via an arbitrary network such asthe Internet. Refer to Non-Patent Literature 1 describing the secondaryusage of the TV white space for an exemplary specification of the dataserver like this.

The secondary system manager (SSM) 100 is a communication control devicehaving a role as a manager managing the secondary usage of a frequencychannel. The SSM 100 allocates the transmission power to the respectivesecondary systems so that the interference due to operating thesecondary system may not give an excessive influence to the primarysystem. The SSM 100 can access to the data server 30 via a network suchas the Internet, for example, and acquires data used for transmissionpower allocation from the data server 30. In addition, the SSM 100 iscommunicably connected with also the respective master nodes 200. Then,the SSM 100, in response to a request from the master node 200 orprimary system, or periodically, allocates the transmission power to thesecondary system. Note that, without limited to the example of FIG. 3,the SSM 100 may be mounted on physically the same device as the dataserver 30 or any master node 200.

FIG. 4 is a sequence diagram illustrating an exemplary schematic flow ofa communication control processing performed in the communicationcontrol system.

First, the master node 200 registers information of the secondary systemin the data server 30 at the start of the secondary usage (step S10).The information registered here includes, for example, an ID, class andposition of a device starting the secondary usage and the like.Moreover, in response to the registration of the information on thesecondary system, the data server 30 notifies the master node 200 ofinformation for configuring the secondary system such as a list ofchannel numbers of secondarily usable frequency channels, acceptablemaximum transmission power and spectrum mask.

Further, the SSM 100 receives information on the primary system from thedata server 30 periodically, for example, and uses the receivedinformation to update information stored in itself (step S11). Here, thereceived information may include one or more of the position data of theprimary transmission station 10, height of an antenna, width of theguard area, list of channel numbers of the frequency channels,acceptable interference amount of the primary system, list of IDs of theregistered master nodes 200, and other parameters. Here, the SSM 100 mayindirectly receive all or a part of the information on the primarysystem (e.g., list of channel numbers) from the master node 200.

Next, a request for power allocation is transmitted from the master node200 to the SSM 100 (step S12). When a response is returned to therequest for power allocation, mutual authentication and applicationlevel information are exchanged between the SSM 100 and the master node200 (step S13). Additionally, the information on the secondary system istransmitted from the master node 200 to the SSM 100 (step S14). Theinformation transmitted here may include an ID, class position data ofthe master node 200, channel number of the frequency channel (the usechannel) selected by the master node 200, and a desired communicationdistance, for example.

Next, the SSM 100 performs the power allocation on the basis of theinformation acquired from the data server 30 and master node 200 (stepS15). The power allocation processing here by the SSM 100 will bedescribed in detail later. Next, the SSM 100 notifies the master node200 of a result of the power allocation (step S16).

Next, the master node 200 configures the secondary system on the basisof the power allocation result notified by the SSM 100, and starts tooperate the secondary system (step S17). Moreover, the master node 200reports a result of the secondary system configuration to the SSM 100(step S18). The SSM 100 updates the information on the secondary systemstored in itself in response to the report from master node 200 (stepS19).

2. EXEMPLARY CONFIGURATION OF SECONDARY SYSTEM MANAGER

FIG. 5 is a block diagram illustrating an exemplary configuration of thesecondary system manager (SSM) 100 illustrated in FIG. 3. With referenceto FIG. 5, the SSM 100 includes a communication unit 110, a control unit120, and a storage unit 180. The control unit 120 includes aninformation acquisition unit 130, a determination unit 140, and asecondary control unit 150.

[2-1. Explanation of Units] (1) Communication Unit

The communication unit 110 is a communication interface forcommunication of the SSM 100 with the data server 30 and with the masternode 200. Communication between the SSM 100 and the data server 30, andbetween the SSM 100 and the master node 200 may be achieved by any of awired communication or wireless communication, or a combination thereof.

(2) Information Acquisition Unit

The information acquisition unit 130 acquires various information itemsthe SSM 100 uses for allocating the transmission power to the secondarysystem from the data server 30 and the master node 200 of the secondarysystem. For example, the information acquisition unit 130 receives theinformation on the primary system from the data server 30. Theinformation on the primary system includes a first informationconcerning the guard area for the primary system. In addition, forexample, the information acquisition unit 130 receives the informationon the secondary system from the master node 200 of the secondarysystem. The information on the secondary system includes a secondinformation concerning the position of the master node 200. Then, theinformation acquisition unit 130 outputs the acquired information to thedetermination unit 140.

(3) Determination Unit

The determination unit 140 uses the first and second informationacquired by the information acquisition unit 130 to determine whether ornot an interval between a reference point of the primary system and themaster node 200 meets a condition which depends on the width of theguard area for the primary system and the communication distance assumedfor the secondary system. Then, the determination unit 140 outputs adetermination result to the secondary control unit 150. The referencepoint of the primary system may be typically the closest point to themaster node 200 on the outer border 14 of the guard area. Alternatively,the reference point may be any point defined within the service area orguard area for the primary system.

The above condition used by the determination unit 140 may be expressedusing the parameter regarding the distance illustrated in FIG. 6. In theexample of FIG. 6, a distance D1 represents the width of the guard area.A distance D2 represents an interval between the above reference pointand the master node 200. In this description, such interval D2 isreferred to as a marginal distance. FIG. 6 also shows a communicationdistance Rprm of the primary system (e.g., radius of the service area)and a communication distance Rsec assumed for the secondary system. Thecommunication distance Rsec assumed for the secondary system may be, forexample, a communication distance desired for the secondary systemnotified to the SSM 100 by the master node 200. Alternatively, thecommunication distance Rsec assumed for the secondary system may be heldin the SSM 100 in advance. The communication distance Rsec held in theSSM 100 in advance may be, for example, an acceptable communicationdistance about the secondary system.

In the example of FIG. 6, assume that a next conditional expression (1)holds between the width of the guard area D1, marginal distance D2, andcommunication distance Rsec, for example. Here, in various conditionalexpressions illustrated in this description, an inequality sign may beused instead of an equality sign.

D ₂≧2·R _(sec) −D ₁  (1)

In this case, even if the slave node positioned around an edge of theservice area for the secondary system uses the same transmission poweras the master node, the wireless signal (SIG in the figure) transmittedfrom the slave node does not practically reach the service area for theprimary system. Therefore, the slave node can easily use the sametransmission power as the master node, allowing a complex control of thetransmission power to not be needed for the slave node.

Here, if the primary system does not have the guard area, the width ofthe guard area D1=0 holds. In this case, the reference point may be anypoint on the outer border 12 of the service area for the primary system(typically, the closest point to master node 200). The first informationconcerning a position of the guard area for the primary system mayinclude information indicating that the primary system does not have theguard area.

In addition, as a next expression, a weight coefficient may beintroduced to the conditional expression (1).

D ₂≧2α_(sec) ·R _(sec)−α₁ D ₁  (2)

If the right side of the conditional expression (2) becomes larger owingto the weight coefficient in the conditional expression (2), a risk ofthe interference is more reduced. Alternatively, for example, if noprimary reception station exists around the edge of the service area forthe primary system, the weight coefficient may be set such that theright side of the conditional expression (2) becomes smaller.

To be more general, these conditional expressions may be expressed by afunction as follows.

D ₂ ≧Th ₁ =f(R _(sec) ,D ₁)  (3)

According to a conditional expression (3), the determination unit 140uses the first and second information to determine whether or not themarginal distance D2 exceeds a threshold Th1 set depending on the widthof the guard area D1 and communication distance Rsec. Note that if theprimary system has the guard area (that is, D1>0), the determinationunit 140 may uses a next conditional expression (4) or (5) instead ofthe conditional expressions (1) to (3).

D ₂ ≧R _(sec) +D ₁ and D ₁ ≧R _(sec)  (4)

D ₂ ≧R _(sec) and D ₁ ≧R _(sec)  (5)

If the conditional expression (4) or (5) is met, the above describedconditional expression (1) is inevitably met. Therefore, in these casesalso, even if the slave node positioned around the edge of the servicearea for the secondary system uses the same transmission power as themaster node, the wireless signal transmitted from the slave node doesnot practically reach the service area for the primary system.

(4) Secondary Control Unit

The secondary control unit 150 controls the operation of the secondarysystem performed by the master node 200 through signaling with themaster node 200. For example, in this embodiment, if the marginaldistance D2 about the master node 200 meets the above describedcondition, the secondary control unit 150 controls the master node 200to operate the secondary system with a given transmission power. A giventransmission power may be typically a transmission power correspondingto the above communication distance R_(sec) (able to accomplish theabove communication distance R_(sec)). A given transmission power heremay be applied to not only the master node 200 but also the slave node.

If the marginal distance D2 about the master node 200 does not meet theabove described condition, the secondary control unit 150 may carry outany of three measures described below. That is, first, the secondarycontrol unit 150 may instruct the master node 200 to use a transmissionpower lower than the transmission power corresponding to the abovecommunication distance R_(sec). Second, the secondary control unit 150may suggest usage of other frequency channels to the master node 200.Third, the secondary control unit 150 may refuse to operate thesecondary system. According to the first measure, although the servicearea for the secondary system becomes smaller, the secondary system canbe ensured to be operated. According to the second measure, while theservice area for the secondary system is maintained, the secondarysystem can be ensured to be operated. However, the second measure iseffective only when available other frequency channels exist. Accordingto the third measure, the secondary system can be extremely easilycontrolled.

The secondary control unit 150 uses the storage unit 180 to manageinformation such as the position of the master node 200, use channel,transmission power allocated to the relevant secondary system andcommunication distance corresponding thereto with respect to eachrespective secondary system being operated. The master node 200 of eachsecondary system, when the configuration of the secondary system iscompleted, reports the configuration of the secondary system to the SSM100. Then, the secondary control unit 150, when notified by the masternode 200 of that the above given transmission power allocated to thesecondary system is excessive for the relevant secondary system, updatesthe transmission power and communication distance about the relevantmanaged secondary system to a lower (shorter) value. This allows alarger amount of transmission power to be allocated to other nearsecondary systems. On the other hand, if the transmission power used inthe configured secondary system is larger than the transmission powerallocated to the relevant secondary system, the secondary control unit150 takes measures against violation of primary system protection (e.g.,warning or registration of violating device to the data server 30 andthe like).

The secondary control unit 150 may notify the master node 200 of a valueof the assumed communication distance Rsec and the width of the guardarea D1. The value of the communication distance Rsec here may be heldthe SSM 100 in advance. This allows, in a case, for example, where themaster node 200 is movable, the master node 200 to move such that themarginal distance D2 meets the above described condition and the masternode 200 to ensure to voluntarily operate the secondary system.

(5) Storage Unit

The storage unit 180 stores a program and data for operation for the SSM100 using a storage medium such as a hard disk or semiconductor memory.

Here, theses components of the SSM 100 shown in FIG. 5 are merelyexamples. That is, the SSM 100 may additionally include components notshown, and a part of the components may be omitted from theconfiguration of the SSM 100.

[2-2. Flow of Process]

In this section, a description will be given of an illustrative threescenarios of the power allocation processing by the SSM 100.

(1) First Scenario

FIG. 7A is a flowchart illustrating a first scenario of the powerallocation processing by the SSM 100 according to this embodiment.

In the first scenario, first, the information acquisition unit 130acquires the information on the primary system received by thecommunication unit 110 from the data server 30 (step S101). Theinformation on the primary system includes the first informationconcerning the position of the guard area for the primary system. Next,the information acquisition unit 130 acquires the information on thesecondary system received by the communication unit 110 from the masternode 200 of the secondary system (step S102). The information on thesecondary system includes the second information concerning the positionof the master node 200.

Next, the determination unit 140 uses the acquired first and secondinformation to determine whether or not the marginal distance D2 meetsthe above described predetermined condition (e.g., any of theconditional expressions (1) to (5)) which depends on the width of theguard area D1 for the primary system and the communication distance Rsecassumed for the secondary system (step S103). A value of the marginaldistance D2 is calculated as an interval between the reference point ofthe primary system and the master node 200. The reference point of theprimary system may be decided as, for example, the closest point to themaster node 200 on the outer border of the guard area using the firstand second information.

If the marginal distance D2 is determined to meet a predeterminedcondition at step S103, the secondary control unit 150 allocates a giventransmission power corresponding to the communication distance Rsec tothe secondary system (step S104). Then, the secondary control unit 150permits the master node 200 to operate the secondary system (step S105).

Next, the secondary control unit 150 acquires the report on theconfiguration of the secondary system from the master node 200 havingconfigured the secondary system (step S106). Then, the secondary controlunit 150 verifies there is no violation of primary system protection(step S107). If there is no violation of primary system protection, thesecondary control unit 150 updates the information on the secondarysystem which is managed in the storage unit 180 (step S108). On theother hand, there is any violation of primary system protection, thesecondary control unit 150 takes measures against the violation (stepS109).

In addition, in the first scenario, if the marginal distance D2 isdetermined to not meet a predetermined condition at step S103, thesecondary control unit 150 notifies the master node 200 of the operationof the secondary system being refused (step S110). In this case, thesecondary system does not start be operated by the master node 200.

(2) Second Scenario

FIG. 7B is a flowchart illustrating a second scenario of the powerallocation processing by the SSM 100 according to this embodiment.Processes from step S101 to step S109 in the second scenario are similarto those in the first scenario.

In the second scenario, if the marginal distance D2 is determined to notmeet a predetermined condition at step S103, the secondary control unit150 suggests usage of other frequency channels different from thefrequency channel allocated to the primary system to the master node 200(step S111). If the master node 200 accepts the usage of anotherfrequency channel, the secondary system starts to be operated on therelevant another frequency channel.

(3) Third Scenario

FIG. 7C is a flowchart illustrating a third scenario of the powerallocation processing by the SSM 100 according to this embodiment.Processes from step S101 to step S109 in the third scenario are similarto those in the first scenario and second scenario.

In the third scenario, if the marginal distance D2 is determined to notmeet a predetermined condition at step S103, the secondary control unit150 calculates a transmission power allocable to the secondary system(step S112). For example, the allocable transmission power may becalculated such that a reception power of the wireless signal from therelevant slave node is equal to or less than the acceptable interferenceamount at the reference point of the primary system even in a case wherethe slave node is positioned around the edge of the service area for thesecondary system. The transmission power which may be calculated herehas a value lower than the transmission power corresponding to the abovecommunication distance R_(sec). Then, the secondary control unit 150instructs the master node 200 to use the calculated transmission power(step S113). If the master node 200 accepts the instruction to use thetransmission power, the relevant transmission power is used to start tooperate the secondary system.

3. EXEMPLARY CONFIGURATION OF MASTER NODE

FIG. 8 is a block diagram illustrating an exemplary configuration of themaster node 200 of the secondary system. With reference to FIG. 8, themaster node 200 includes a network communication unit 210, wirelesscommunication unit 215, control unit 220, and storage unit 280. Thecontrol unit 220 includes a power control unit 250, informationacquisition unit 260, and determination unit 270.

[3-1. Explanation of Units] (1) Network Communication Unit

The network communication unit 210 is a communication interface forcommunication of the master node 200 with the data server 30 and withthe SSM 100. Communication between the master node 200 and the dataserver 30, and between the master node 200 and the SSM 100 may beachieved any of a wired communication or wireless communication, or acombination thereof.

(2) Wireless Communication Unit

The wireless communication unit 215 is a communication interfaceperforming wireless communication with one or more slave nodesparticipating in the secondary system operated by the master node 200.For example, the wireless communication unit 215 broadcasts a controlsignal such as a beacon or reference signal using the transmission powerset by the power control unit 250 described later. The relevant controlsignal includes control information indicating a set value of thetransmission power. The slave node, in receiving the relevant controlsignal, may use the same transmission power as the master node 200 toparticipate in the secondary system operated by the master node 200.

(3) Power Control Unit

The power control unit 250 controls the transmission power for thesecondary system operated by the master node 200. In this embodiment,the power control unit 250 before starting to operate the secondarysystem, registers the information on the secondary system in the dataserver 30. Then, the power control unit 250, for example, selects achannel used for the secondary system from the list of the channelnumbers of the secondarily usable frequency channels provided by thedata server 30. Then, the power control unit 250 requests thetransmission power allocation from the SSM 100. The power control unit250 provides to the SSM 100 the information on the secondary system usedby the SSM 100 for the transmission power allocation. The informationprovided to the SSM 100 includes positional information on the masternode 200 which is measured by a positioning sensor (not shown) such as aGPS (Global Positioning System) sensor or held in the storage unit 280in advance. Moreover, the information provided to the SSM 100 mayinclude the communication distance desired for secondary system to beoperated. Then, the power control unit 250, in being notified of thetransmission power to be allocated when the SSM 100 permits thesecondary system to be operated, the relevant sets transmission power tothe wireless communication unit 215 and starts to operate the secondarysystem.

If the transmission power allocated by the SSM 100 is excessive, thepower control unit 250 may configure the secondary system with a lowertransmission power instead of the transmission power allocated by theSSM 100. In that case, the power control unit 250, in reporting theconfiguration of the secondary system, notifies the SSM 100 of a valueof the transmission power actually used.

Moreover, the power control unit 250, if instructed by the SSM 100 touse lower than the transmission power corresponding to the desiredcommunication distance or suggested changing the use channel, determineswhether or not the instruction or suggestion is to be accepted. In thecase where the instruction or suggestion is accepted, if a desiredcommunication service cannot be achieved, the secondary system may stopfrom being operated. On the other hand, if the desired communicationservice can be achieved even in the case where the instruction orsuggestion is accepted, the power control unit 250 may start to operatethe secondary system with the instructed transmission power or onanother frequency channel.

(4) Information Acquisition Unit

The information acquisition unit 260 and the determination unit 270 maybe optionally provided in order to determine the condition in the masternode 200 about the marginal distance D2. The information acquisitionunit 260 acquires the first information concerning the position of theguard area for the primary system from the SSM 100. Additionally, theinformation acquisition unit 260 acquires the second informationconcerning the position of the master node 200 measured by thepositioning sensor or held in the storage unit 280 in advance. Then, theinformation acquisition unit 260 outputs the acquired information to thedetermination unit 270.

(5) Determination Unit

The determination unit 270 uses the first information and secondinformation acquired by the information acquisition unit 260 todetermine whether or not the marginal distance D2 about the master node200 meets a condition which depends on the width of the guard area D1and the communication distance Rsec assumed for the secondary system.Here, the communication distance Rsec assumed for the secondary systemmay be, for example, a communication distance desired for secondarysystem. Alternatively, the communication distance Rsec assumed for thesecondary system may be the communication distance about the secondarysystem (e.g., acceptable communication distance) which is notified tothe master node 200 by the SSM 100. The above condition used by thedetermination unit 270 may be, for example, a condition expressed by anyof the above described conditional expressions (1) to (5). That is, thedetermination unit 270 uses the first information and second informationto determine whether or not the marginal distance D2 exceeds thethreshold set depending on the width of the guard area D1 and thecommunication distance Rsec. Then, the determination unit 270 outputs adetermination result to the power control unit 250.

If the marginal distance D2 is determined to meet the above condition bythe determination unit 270, the power control unit 250 may use thetransmission power corresponding to the communication distance Rsec toconfigure the secondary system. On the other hand, if the marginaldistance D2 is determined to not meet the above condition by thedetermination unit 270, the power control unit 250, after the masternode 200 moves or with the communication distance being shortened,controls the determination unit 270 to again determine the conditionabout the marginal distance D2. In this way, in the case wheredetermination of the condition about the marginal distance D2 is made bythe master node 200, the determination about the marginal distance D2 inthe SSM 100.

(6) Storage Unit

The storage unit 280 stores a program and data for operation for themaster node 200 using a storage medium such as a hard disk orsemiconductor memory.

[3-2. Flow of Process]

In this section, a description will be given of two examples of the flowof the communication control processing by the above described masternode 200. In a first example, the determination about the marginaldistance D2 is made by the SSM 100. In a second example, thedetermination about the marginal distance D2 is made by the master node200.

(1) Condition Determination by SSM

FIG. 9 is a flowchart illustrating the first example of the flow of thecommunication control processing by the master node 200. First, thepower control unit 250 requests the transmission power allocation fromthe SSM 100 (step S201), and transmits the information on the secondarysystem to the SSM 100 (step S202). The information transmitted here mayinclude information such as the positional information on the masternode 200, communication distance desired for the secondary system, anduse channel.

Next, when a response from the SSM 100 is received, the power controlunit 250 determines whether or not the secondary system is permitted tobe operated (step S203). If the secondary system is permitted to beoperated, the power control unit 250 further determines whether or notthe allocated transmission power is proper (step S204). For example, ifan excessive transmission power is allocated, the power control unit 250may set a unique transmission power to accomplish the desiredcommunication distance to the wireless communication unit 215 (stepS205). On the other hand, if the allocated transmission power is proper,the power control unit 250 sets the relevant allocated transmissionpower to the wireless communication unit 215 (step S206).

If the secondary system is not permitted to be operated at step S203,the power control unit 250 determines whether or not to operate thesecondary system with a lower transmission power or on another frequencychannel (step S207). In the case where the secondary system is operatedwith a lower transmission power or on another frequency channel, thepower control unit 250 sets a lower transmission power or a newfrequency channel to the wireless communication unit 215 (step S208).

If the transmission power and the frequency channel are set at stepS205, step S206, or step S208, the master node 200 starts to operate thesecondary system (step S209). Then, the power control unit 250 reportsthe configuration of the secondary system to the SSM 100 (step S210).

(2) Condition Determination by Master Node

FIG. 10 is a flowchart illustrating the second example of the flow ofthe communication control processing by the master node 200. First, theinformation acquisition unit 260 acquires the first informationconcerning the position of the guard area for the primary system fromthe SSM 100 (step S221). Additionally, the information acquisition unit260 acquires the second information concerning the position of themaster node 200 (step S222)

Next, the determination unit 270 uses the acquired first information andsecond information to determines whether or not the marginal distance D2about the master node 200 meets a condition which depends on the widthof the guard area D1 and the communication distance Rsec assumed for thesecondary system (step S223). Here, if the marginal distance D2 meetsthe above condition, the power control unit 250 sets the transmissionpower corresponding to the communication distance Rsec to the wirelesscommunication unit 215 (step S224). Then, the master node 200 starts tooperate the secondary system (step S225). On the other hand, if themarginal distance D2 does not meet the above condition at step S223, thecommunication distance Rsec may be changed to shorter value and theposition of the master node 200 is updated depending on move of themaster node 200 (step S226). After that, the determination unit 270 mayagain make the determination of step S223.

4. APPLICATION TO INTERFERENCE CONTROL BETWEEN SECONDARY SYSTEMS

In the above described embodiment, through the condition determinationabout the marginal distance D2 which corresponds to an interval betweenthe reference point of the primary system and the master node 200, thetransmission power able to be mutually used by the master node and slavenode is easily allocated to the secondary system. This can prevent thewireless signal transmitted from the slave node from giving an excessiveinterference to the primary reception station. The mechanism like this,as is described in this section, can be also applicable in order toprevent an interference between the secondary systems.

FIG. 11 is an explanatory diagram for explaining an exemplary parameterregarding a distance used for an interference control between thesecondary systems. FIG. 11 shows a communication distance RsecA assumedfor the secondary system as a transmission power allocation target and acommunication distance RsecB of a secondary system near the relevantsecondary system (hereinafter, referred to as near system). A distanceD3 represents a width of the guard area temporarily set for the nearsystem. The width of the guard area D3 for the near system may bedefined as a fixed value in advance. Alternatively, the width of theguard area D3 for the near system may be variably decided by multiplyingthe communication distance RsecB of the relevant near system by aconstant rate, for example. The distance D2 is a marginal distance whichcorresponds to an interval between the reference point on the outerborder of the guard area temporarily set (on the outer border of theservice area if D3=0) and the master node 200.

In the example of FIG. 11, if a next conditional expression (6) holdsbetween the marginal distance D2, width of the guard area D3, andcommunication distance Rsec, even if the slave node uses the sametransmission power as the master node, the wireless signal transmittedfrom the relevant slave node does not practically reach of the servicearea for the near system.

D ₂≧2·R _(sec) −D ₃  (6)

Therefore, the slave node can easily use the same transmission power asthe master node, allowing a complex control of the transmission power tonot be needed for the slave node. In addition, as a next expression, aweight coefficient may be introduced to the conditional expression (6).

D ₂≧2α_(sec) ·R _(sec)−α₃ D ₃  (7)

To be more general, these conditional expressions may be expressed by afunction as follows.

D ₂ ≧Th ₃ =f(R _(see) ,D ₃)  (8)

According to a conditional expression (8), the determination unit 140 inthe SSM 100 determines whether or not the marginal distance D2 exceeds athreshold Th₃ set depending on the width of the guard area D3temporarily set for the near system and the communication distanceR_(sec). Then, if the marginal distance D2 exceeds the threshold Th₃,the secondary control unit 150 controls the master node 200 to operatethe secondary system with a given transmission power. A giventransmission power may be typically a transmission power correspondingto the above communication distance R_(sec). Here, a given transmissionpower may be applied to not only the master node 200 but also the slavenode. Note that the determination unit 140 may use a next conditionalexpression (9) or (10) when D₃>0, instead of the conditional expressions(6) to (8).

D ₂ ≧R _(sec) +D ₃ and D ₃ ≧R _(sec)  (9)

D ₂ ≧R _(sec) and D ₃ ≧R _(sec)  (10)

FIG. 12 is a flowchart illustrating an exemplary flow of the powerallocation processing by the SSM 100 for the interference controlbetween the secondary systems.

With reference to FIG. 12, first, the information acquisition unit 130acquires the information on the secondary system from the master node200 as a transmission power allocation target (step S301). Theinformation acquired here includes the second information concerning theposition of the master node 200. Next, the information acquisition unit130 acquires information on the near system which is managed in thestorage unit 180 (step S302). The information acquired here includes thefirst information concerning the position of the service area which isused to set the guard area to the near system (e.g., informationindicating position of the master node of the near system andcommunication distance). Then, the determination unit 140 temporarilysets the guard area to the near system (step S303).

Next, the determination unit 140 determines whether or not the marginaldistance D2 about the master node 200 the above described predeterminedcondition (e.g., any of the conditional expressions (6) to (10)) whichdepends on the width of the guard area D3 for the near system and thecommunication distance Rsec assumed for the secondary system (stepS304).

If the marginal distance D2 is determined to meet a predeterminedcondition at step S304, the secondary control unit 150 allocates a giventransmission power corresponding to the communication distance Rsec tothe secondary system (step S305). Then the secondary control unit 150permits the master node 200 to operate the secondary system (step S306).

On the other hand, if the marginal distance D2 is determined to not meeta predetermined condition at step S304, the secondary control unit 150calculates a transmission power allocable (step S306). For example, thetransmission power allocable may be calculate such that a receptionpower of the wireless signal from the relevant slave node is equal to orless than the acceptable interference amount at the reference point ofthe near system even in a case where the slave node is positioned aroundthe edge of the service area for the secondary system. The transmissionpower which may be calculated here has a value lower than thetransmission power corresponding to the above communication distanceRsec. Then, the secondary control unit 150 instructs the master node 200to use the calculated transmission power (step S307). Here, instead ofstep S306 and S307, other frequency channels different from thefrequency channel allocated to the near system may be suggested, or thesecondary system may be refused to be operated.

After that, the secondary control unit 150 acquires a report on theconfiguration of the secondary system from the master node 200 havingconfigured the secondary system (step S308). Then, the secondary controlunit 150 updates the information on the secondary system which ismanaged in the storage unit 180 (step S309).

5. CONCLUSION

One embodiment and applicable example thereof of the technology of thepresent invention are described in detail so far with using FIG. 1 toFIG. 12. According to this embodiment, determined is whether or not themarginal distance which corresponds to an interval between the referencepoint of the primary system or near system and the master node of thesecondary system meets a condition which depends on the width of theguard area and the communication distance assumed for the relevantsecondary system, and if the relevant condition is met, the secondarysystem is operated with a given transmission power. This prevents thewireless signal transmitted from the relevant slave node from causing anexcessive interference even if the slave node of the secondary systemuses the transmission power equivalent to that of the master node.Therefore, the slave node can be allowed to easily use a transmissionpower equivalent to the transmission power allocated to the master node.This means that eliminated is the necessity to provide a complextransmission power calculation mechanism for each of the master node andthe slave node. Therefore, introduction of the secondary system isfacilitated. In addition, even if the position of the slave node is notknown at the start of operation of the secondary system, the wirelesssignal transmitted from the slave node can be prevented from causing anexcessive interference.

The above assumed communication distance may be the desired distancenotified to the secondary system manager by the master node. In thatcase, if the above condition is met, the transmission powercorresponding to a communication distance desired for the master nodecan be easily allocated to the secondary system. In addition, the aboveassumed communication distance may be a communication distance stored inthe secondary system manager using the storage medium in advance. Inthat case, if the above condition is met, the transmission powercorresponding to the relevant communication distance can be easilyallocated to the secondary system.

If the above condition is determined to not be met, the master node maybe instructed to use a transmission power lower than the transmissionpower corresponding to the above assumed communication distance.Therefore, only in the case where the above condition is not met, thesecondary system manager can perform detail calculation of transmissionpower with taking into consideration the position of the master node,path loss and the like. That is, a calculation load on the secondarysystem manager may be suppressed.

Moreover, the determination of the above marginal distance may be madeby the master node of the secondary system instead of the secondarysystem manager. In that case, the master node (or a provider who locatesthe master node) can voluntarily adjust the configuration of thesecondary system. Further, a load on the secondary system manager can besuppressed, allowing an overhead of signaling between the manager andthe master node to be reduced.

A sequence of control processing by each apparatus described herein maybe realized by using software, hardware, or a combination of softwareand hardware. Programs constituting software are stored in, for example,a storage medium provided inside or outside each apparatus in advance.Then, for example, each program is read into RAM (Random Access Memory)during execution and executed by a processor such as CPU (CentralProcessing Unit).

The preferred embodiments of the present invention have been describedabove with reference to the accompanying drawings, whilst the presentinvention is not limited to the above examples, of course. A personskilled in the art may find various alternations and modificationswithin the scope of the appended claims, and it should be understoodthat they will naturally come under the technical scope of the presentinvention.

Additionally, the present disclosure may also be configured as below.

(1) A communication control device including:

an information acquisition unit acquiring first information and secondinformation, the first information concerning a position a guard areafor a first wireless communication system, the second informationconcerning a position of a master node of a second wirelesscommunication system which is secondarily operated using a frequencychannel used by the first wireless communication system;

a determination unit determining, using the first information and thesecond information acquired by the information acquisition unit, whetheror not an interval between a reference point of the first wirelesscommunication system and the master node meets a condition which dependson a width of the guard area and a communication distance assumed forthe second wireless communication system; and

a control unit causing the second wireless communication system to beoperated with a given transmission power if the determination unitdetermines the interval meets the condition.

(2) The communication control device according to (1),

wherein the communication control device is a manager managing secondaryusage of the frequency channel, and

wherein the communication distance is a desired distance notified to themanager by the master node.

(3) The communication control device according to (1),

wherein the communication control device is a manager managing asecondary usage of the frequency channel, and

wherein the communication distance is a communication distance about asecondary system which is held in the communication control device inadvance.

(4) The communication control device according to (2) or (3),

wherein if the determination unit determines the condition is not met,the control unit instructs the master node to use a transmission powerlower than a transmission power corresponding to the communicationdistance.

(5) The communication control device according to (2) or (3),

wherein if the determination unit determines the condition is not met,the control unit suggests usage of another frequency channel to themaster node.

(6) The communication control device according to (2) or (3),

wherein if the determination unit determines the condition is not met,the control unit does not permit the second wireless communicationsystem to be operated.

(7) The communication control device according to (1),

wherein the communication control device is the master node, and

wherein the communication distance is a communication distance about asecondary system notified to the master node by a manager managing thesecondary usage of a frequency channel.

(8) The communication control device according to any one of (1) to (6),

wherein the communication control device is a manager managing asecondary usage of the frequency channel, and

wherein after the determination unit determines the condition is met,the control unit, when notified by the master node of that the giventransmission power is excessive for the second wireless communicationsystem, updates the given transmission power to a lower value.

(9) The communication control device according to any one of (1) to (8),

wherein the first wireless communication system is a primary system, and

wherein the second wireless communication system is a secondary system.

(10) The communication control device according to any one of (1) to(8),

wherein each of the first wireless communication system and the secondwireless communication system is a secondary system secondarily operatedusing a frequency channel allocated to a primary system.

(11) The communication control device according to (10),

wherein the width of the guard area for the first wireless communicationsystem is a fixed value or a variable value decided depending on of acommunication distance the first wireless communication system.

(12) The communication control device according to any one of (1) to(11),

wherein the reference point exists on an outer border of the guard area,or on an outer border of a service area for the first wirelesscommunication system if the first wireless communication system does nothave the guard area.

(13) The communication control device according to (12),

wherein the condition is a condition based on comparison between theinterval and a difference obtained by subtracting the width of the guardarea from twice the communication distance assumed for the secondwireless communication system.

(14) A communication control method, for a communication control devicecontrolling a second wireless communication system which is secondarilyoperated using a frequency channel used by a first wirelesscommunication system, the method comprising:

acquiring first information and second information, the firstinformation concerning a position of a guard area for the first wirelesscommunication system, the second information concerning a position of amaster node of the second wireless communication system;

determining, using the acquired first information and the secondinformation, whether or not an interval between a reference point of thefirst wireless communication system and the master node meets acondition which depends on a width of the guard area and a communicationdistance assumed for the second wireless communication system; and

causing the second wireless communication system to be operated with agiven transmission power if the interval is determined to meet thecondition.

(15) A communication control system comprising:

a master node of a second wireless communication system which issecondarily operated using a frequency channel used by a first wirelesscommunication system; and

a communication control device which controls operation of the secondwireless communication system performed by the master node,

wherein the communication control device includes

-   -   an information acquisition unit acquiring first information and        second information, the first information concerning a position        of a guard area for the first wireless communication system, the        second information concerning a position of the master node,    -   a determination unit determining, using the first information        and the second information acquired by the information        acquisition unit, whether or not an interval between a reference        point of the first wireless communication system and the master        node meets a condition which depends on a width of the guard        area and a communication distance assumed for the second        wireless communication system, and    -   a control unit causing the master node to operate the second        wireless communication system with a given transmission power if        the determination unit determines the interval meets the        condition.

REFERENCE SIGNS LIST

-   1 communication control system-   30 data server-   100 communication control device (secondary system manager)-   130 information acquisition unit-   140 determination unit-   150 control unit-   200 communication control device (master node)-   250 control unit-   260 information acquisition unit-   270 determination unit-   202 slave node

1. A communication control device comprising: an information acquisitionunit acquiring first information and second information, the firstinformation concerning a position a guard area for a first wirelesscommunication system, the second information concerning a position of amaster node of a second wireless communication system which issecondarily operated using a frequency channel used by the firstwireless communication system; a determination unit determining, usingthe first information and the second information acquired by theinformation acquisition unit, whether or not an interval between areference point of the first wireless communication system and themaster node meets a condition which depends on a width of the guard areaand a communication distance assumed for the second wirelesscommunication system; and a control unit causing the second wirelesscommunication system to be operated with a given transmission power ifthe determination unit determines the interval meets the condition. 2.The communication control device according to claim 1, wherein thecommunication control device is a manager managing secondary usage ofthe frequency channel, and wherein the communication distance is adesired distance notified to the manager by the master node.
 3. Thecommunication control device according to claim 1, wherein thecommunication control device is a manager managing a secondary usage ofthe frequency channel, and wherein the communication distance is acommunication distance about a secondary system which is held in thecommunication control device in advance.
 4. The communication controldevice according to claim 2, wherein if the determination unitdetermines the condition is not met, the control unit instructs themaster node to use a transmission power lower than a transmission powercorresponding to the communication distance.
 5. The communicationcontrol device according to claim 2, wherein if the determination unitdetermines the condition is not met, the control unit suggests usage ofanother frequency channel to the master node.
 6. The communicationcontrol device according to claim 2, wherein if the determination unitdetermines the condition is not met, the control unit does not permitthe second wireless communication system to be operated.
 7. Thecommunication control device according to claim 1, wherein thecommunication control device is the master node, and wherein thecommunication distance is a communication distance about a secondarysystem notified to the master node by a manager managing the secondaryusage of a frequency channel.
 8. The communication control deviceaccording to claim 1, wherein the communication control device is amanager managing a secondary usage of the frequency channel, and whereinafter the determination unit determines the condition is met, thecontrol unit, when notified by the master node of that the giventransmission power is excessive for the second wireless communicationsystem, updates the given transmission power to a lower value.
 9. Thecommunication control device according to claim 1, wherein the firstwireless communication system is a primary system, and wherein thesecond wireless communication system is a secondary system.
 10. Thecommunication control device according to claim 1, wherein each of thefirst wireless communication system and the second wirelesscommunication system is a secondary system secondarily operated using afrequency channel allocated to a primary system.
 11. The communicationcontrol device according to claim 10, wherein the width of the guardarea for the first wireless communication system is a fixed value or avariable value decided depending on of a communication distance thefirst wireless communication system.
 12. The communication controldevice according to claim 1, wherein the reference point exists on anouter border of the guard area, or on an outer border of a service areafor the first wireless communication system if the first wirelesscommunication system does not have the guard area.
 13. The communicationcontrol device according to claim 12, wherein the condition is acondition based on comparison between the interval and a differenceobtained by subtracting the width of the guard area from twice thecommunication distance assumed for the second wireless communicationsystem.
 14. A communication control method, for a communication controldevice controlling a second wireless communication system which issecondarily operated using a frequency channel used by a first wirelesscommunication system, the method comprising: acquiring first informationand second information, the first information concerning a position of aguard area for the first wireless communication system, the secondinformation concerning a position of a master node of the secondwireless communication system; determining, using the acquired firstinformation and the second information, whether or not an intervalbetween a reference point of the first wireless communication system andthe master node meets a condition which depends on a width of the guardarea and a communication distance assumed for the second wirelesscommunication system; and causing the second wireless communicationsystem to be operated with a given transmission power if the interval isdetermined to meet the condition.
 15. A communication control systemcomprising: a master node of a second wireless communication systemwhich is secondarily operated using a frequency channel used by a firstwireless communication system; and a communication control device whichcontrols operation of the second wireless communication system performedby the master node, wherein the communication control device includes aninformation acquisition unit acquiring first information and secondinformation, the first information concerning a position of a guard areafor the first wireless communication system, the second informationconcerning a position of the master node, a determination unitdetermining, using the first information and the second informationacquired by the information acquisition unit, whether or not an intervalbetween a reference point of the first wireless communication system andthe master node meets a condition which depends on a width of the guardarea and a communication distance assumed for the second wirelesscommunication system, and a control unit causing the master node tooperate the second wireless communication system with a giventransmission power if the determination unit determines the intervalmeets the condition.